Optimal Sensing Strategy Against Collision With Primary User in Cognitive Radio Systems

The cognitive radio (CR) system needs to optimally set the sensing period and sensing time, to efficiently utilize the channel while protecting a primary user (PU). The optimal sensing period for maximizing the effective throughput of the CR system depends on not only the on/off pattern of the PU and the sensing error probabilities but also the size of a data packet, the transmission rate, and the forward error correction capability. In this paper, we mathematically derive the optimal sensing period while taking all of these factors into account. On the basis of this optimal period, we design the sensing strategy under which the CR user has the breaks for sensing during a data packet transmission. With the proposed sensing strategy, the CR system can protect the PU very well while achieving the high effective throughput.